The row/column bounds (for a screen window box) are changed from
'offset one' to 'offset zero' and bound to the screen size using:
v->xs = min_t(u16, v->xs - 1, vc->vc_cols - 1);
This has the side effect of converting zero to the limit.
A check I'm adding to min_t() reports that (u16)(v->xs - 1) (etc)
discards signiticant bits (because v->xs is promoted to 'int' before
the addition).
If v->xs is zero (it comes from userspace) it converts -1 to 0xffff.
This is then bounded to 'vc->vc_cols - 1' which will be fine.
Replace with:
v->xs = umin(v->xs - 1, vc->vc_cols - 1);
which again converts a -1 to unsigned - this time to 0xffffffff,
with the same overall effect.
Whether zero is meant to mean the 'maximum size' is unknown.
I can't find any documentation for the ioctl and it pre-dates git.
Detected by an extra check added to min_t().
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://patch.msgid.link/20251119224140.8616-28-david.laight.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Support "\e[?1049h" and "\e[?1049l" escape codes.
This patch allows programs to enter and leave alternate screens.
This feature is widely available in graphical terminal emulators and mostly
used by fullscreen terminal-based user interfaces such as text editors.
Most editors such as vim and nano assume this escape code in not supported
and will not try to print the escape sequence if TERM=linux.
To try out this patch, run `TERM=xterm-256color vim` inside a VT.
Signed-off-by: Calixte Pernot <calixte.pernot@grenoble-inp.org>
Link: https://lore.kernel.org/r/20250825125607.2478-3-calixte.pernot@grenoble-inp.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Having all the new guards, use them in the vt code. This improves
readability, makes error handling easier, and marks locked portions of
code explicit.
A local free_page_ptr __free guard is introduced for
__get_free_page/free_page (with proper casts). This could be made public
in include/. But I am not sure if there are more possible users, so
keeping completely private here.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250814072456.182853-16-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The maximum number of keycodes got bumped to 256 a very long time ago,
but the default keymaps were never adjusted to match. This is causing
the kernel to interpret keycodes above 127 as U+0000 if the shipped
generated keymap is used.
Fix this by mapping all keycodes above 127 to K_HOLE so the kernel
ignores them.
The contents of this patche were generated by rerunning `loadkeys
--mktable --unicode` and only including the changes to map keycodes
above 127 to K_HOLE.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Myrrh Periwinkle <myrrhperiwinkle@qtmlabs.xyz>
Cc: stable <stable@kernel.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250702-vt-misc-unicode-fixes-v1-2-c27e143cc2eb@qtmlabs.xyz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The console dimension and cursor position are available through the
/dev/vcsa interface already. However the /dev/vcsa header format uses
single-byte fields therefore those values are clamped to 255.
As surprizing as this may seem, some people do use 240-column 67-row
screens (a 1920x1080 monitor with 8x16 pixel fonts) which is getting
close to the limit. Monitors with higher resolution are not uncommon
these days (3840x2160 producing a 480x135 character display) and it is
just a matter of time before someone with, say, a braille display using
the Linux VT console and BRLTTY on such a screen reports a bug about
missing and oddly misaligned screen content.
Let's add VT_GETCONSIZECSRPOS for the retrieval of console size and cursor
position without byte-sized limitations. The actual console size limit as
encoded in vt.c is 32767x32767 so using a short here is appropriate. Then
this can be used to get the cursor position when /dev/vcsa reports 255.
The screen dimension may already be obtained using TIOCGWINSZ and adding
the same information to VT_GETCONSIZECSRPOS might be redundant. However
applications that care about cursor position also care about display
size and having 2 separate system calls to obtain them separately is
wasteful. Also, the cursor position can be queried by writing "\e[6n" to
a tty and reading back the result but that may be done only by the actual
application using that tty and not a sideline observer.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Link: https://lore.kernel.org/r/20250520171851.1219676-3-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is comprised of 3 aspects:
- Take note of when applications advertise bracketed paste support via
"\e[?2004h" and "\e[?2004l".
- Insert bracketed paste markers ("\e[200~" and "\e[201~") around pasted
content in paste_selection() when bracketed paste is active.
- Add TIOCL_GETBRACKETEDPASTE to return bracketed paste status so user
space daemons implementing cut-and-paste functionality (e.g. gpm,
BRLTTY) may know when to insert bracketed paste markers.
Link: https://en.wikipedia.org/wiki/Bracketed-paste
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250520171851.1219676-2-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The generated table maps complex characters to their simpler fallback
forms for a terminal display when corresponding glyphs are unavailable.
This includes diacritics, symbols as well as many drawing characters.
Fallback characters aren't perfect replacements, obviously. But they are
still far more useful than a bunch of squared question marks.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250507141535.40655-5-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the Unicode screen buffer, we follow double-width code points with a
space to maintain proper column alignment. This, however, creates
semantic problems when e.g. using cut and paste.
Let's use a better code point for the column padding's purpose i.e. a
zero-width space rather than a full space. This way the combination
retains a width of 2.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250417184849.475581-11-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The generated table maps base character + combining mark pairs to their
precomposed equivalents using Python's unicodedata module.
The default script behavior is to create a table with most commonly used
Latin, Greek, and Cyrillic recomposition pairs only. It is much smaller
than the table with all possible recomposition pairs (71 entries vs 1000
entries). But if one needs/wants the full table then simply running the
script with the --full argument will generate it.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250417184849.475581-8-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Zero-width Unicode code points are causing misalignment in vertically
aligned content, disrupting the visual layout. Let's handle zero-width
code points more intelligently.
Double-width code points are stored in the screen grid followed by a white
space code point to create the expected screen layout. When a double-width
code point is followed by a zero-width code point in the console incoming
bytestream (e.g., an emoji with a presentation selector) then we may
replace the white space padding by that zero-width code point instead of
dropping it. This maximize screen content information while preserving
proper layout.
If a zero-width code point is preceded by a single-width code point then
the above trick is not possible and such zero-width code point must
be dropped.
VS16 (Variation Selector 16, U+FE0F) is special as it typically doubles
the width of the preceding single-width code point. We handle that case
by giving VS16 a width of 1 instead of 0 when that happens.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250417184849.475581-4-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 74045f6658.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 2acaf27cd7.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit e88391f730.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 26c94eb484.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 3a1ab63aa0.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit f2347b0cdf.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 54af55b990.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit cd6937d42b.
A new version of the series was submitted, so it's easier to revert the
old one and add the new one due to the changes invovled.
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
